• by Sarah Mahoney  @mahoney_sarah, August 1, 2016

Even Muggles know that July 31 is Harry Potter’s birthday, and it looks like it will be the best one in years for retailers who love books: Harry Potter and the Cursed Child Parts I & II went on sale this weekend. And with the glowing reviews rolling in, it's likely to be the bestselling book of the year. 

Barnes & Noble, which says the title is its most pre-ordered book since Harry Potter and the Deathly Hallows appeared in 2007, celebrated the big day with fan-favorite "Countdown to Midnight Magic" parties on July 30. And Target was offering the book with an exclusive poster, as well as a Harry Potter shop with the earlier novels, clothing, adult coloring books, Funko figurines, and the earlier films, for a limited time only, on DVD and Blu Ray.

Barnes & Noble says the book has been No. 1 on its BN.com bestseller list, and that it is expected to be Barnes & Noble’s biggest book of the year; industry insiders are making the same prediction about Amazon, especially now that it’s earning such strong reviews.

This one isn’t a novel, but the script of the stage play, written by author J.K. Rowling with John Tiffany and Jack Thorne. The show has opened to rave reviews in London’s West End. (Hubbub leading up to that opening included a plea from creator J.K. Rowlings, also born on July 31, to #KeepTheSecrets.)

“This new story introduces captivating arcs and bold theories that immediately place this sequel squarely in Rowling’s world of simmering, slow-burn machinations,” says Entertainment Weekly. “Thrills aside, the emotional core here is a deeply human one, which Rowling should consider a huge achievement decades in the making.” And the New York Times called it a “compelling, stay-up-all-night read.”

And while this is all terrific news for booksellers, especially B&N, which has been struggling with declining sales, it comes with terrible news for the rest of the world: Rowling says she’s taken Harry, now a 37-year-old dad, on his last run, telling Reuters that the beloved wizard is “done now.”